This invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to developer and toner compositions containing novel crosslinked polyesterimide resins, and reactive extrusion process for the preparation thereof. In embodiments, there are provided in accordance with the present invention toner compositions, especially low melting and broad fusing latitude toner compositions, comprised of certain crosslinked polyesterimide resins and pigment particles comprised of, for example, carbon black, magnetites, or mixtures thereof, cyan, magenta, yellow, blue, green, red, or brown components, or mixtures thereof thereby providing for the development and generation of black and/or colored images. In embodiments, there are provided in accordance with the present invention unsaturated polyesterimide resins of the following formula which resins are selected for the preparation of the crosslinked polyimides ##STR1## wherein x and y represent the number of random repeating segments and can be a number of from about 10 to about 10,000, and preferably up to about 1,000; R' is an alkyl group with from about 1 to about 25 carbon atoms; and R is an alkyl group, oxyalkylene or polyoxyalkylene. The aforementioned unsaturated polyesterimides are then reacted with free radical initiators such as, for example, with peroxides such as benzoyl peroxide and the like to yield crosslinked polyesterimides. Processes for the preparation of the toners of this invention include reactive extrusion process wherein the aforementioned unsaturated polyimide resin is admixed with peroxides, such as benzoyl peroxide, in an amount of from about 0.1 percent to about 3 percent by weight of unsaturated polyesterimide, and then extruded, for instance, utilizing a Davo Twin extruder operated at a barrel temperature of from about 140.degree. C. to about 180.degree. C., thereby converting the linear unsaturated polyimide to the desired crosslinked polyimide followed by the addition of pigment. The toner compositions of the present invention in embodiments possess a number of advantages including low melting characteristics, excellent blocking characteristics of above 120.degree. F., possess excellent nonvinyl-offset properties, and low relative humidity sensitivity such as from about 1.2 to about 3.0. The unsaturated polyesterimides of the present invention can in embodiments be generated by the reaction of at least one alkylene diamine, such as branched JEFFAMINES.TM. available from Texaco Chemicals as JEFFAMINE D-230.TM., D-400.TM., EDR-148.TM., EDR-192.TM., and are believed to be of the following formula ##STR2## EDR-148 n=2;R.dbd.H EDR-192 n=3;R.dbd.H
D-230 n=2,3; R.dbd.CH.sub.3 PA1 D-400 n=5,6; R.dbd.CH.sub.3
The aforementioned polyimides exhibit in embodiments a number average molecular weight of from about 3,000 grams per mole to about 30,000 grams per mole as measured by vapor phase osmometer, have a glass transition temperature of from about 45.degree. C. to about 65.degree. C., and more preferably of from about 50.degree. C. to about 62.degree. C. as measured by the Differential Scanning Calorimeter.
Examples of advantages of the toner composition of the present invention include low fusing temperatures, such as from about 115.degree. C. to about 145.degree. C., and therefore, lower fusing energies are required for fixing thus enabling less power consumption during fusing, and permitting extended lifetimes for the fuser system selected. Furthermore, the toner composition of this invention possesses in embodiments a broad fusing latitude, such as from about 30.degree. C. to about 100.degree. C., with minimal or avoidance of release oil, which inhibits the toner from offsetting onto the fuser rollers usually associated with ghosting or background images on subsequent copies. Additionally, the fused image obtained with the toner compositions of the present invention in embodiments does not substantially offset to vinyl covers, such as those utilized for notebook binders, and possess low humidity sensitivity ratio of from about 1 to about 2.3 as calculated by the ratio of the triboelectric charge in microcoulombs per gram of the developer after placed in a chamber of 20 percent humidity for 48 hours to the triboelectric charge in microcoulombs per gram of the developer after placed in a chamber of 80 percent humidity for 48 hours.
A number of toner resins are known, such as styrene acrylates, styrene methacrylates, polyesters, polyamides, and generally certain polyimides.
Certain polyimide and polyesterimide resins and, more specifically, linear polyesterimide resins are illustrated in U.S. Pat. No. 5,348,831, the disclosure of which is totally incorporated herein by reference. Specifically, the aforementioned copending application discloses linear polyesterimide resin useful for high gloss toner applications wherein glossy images of from about 50 to about 80 gloss units are obtained for certain printing or copying applications, especially wherein pictorial images are desired. The present invention's polyesterimides differ in that, for example, linear unsaturated polyimides are crosslinked to result in toner compositions comprised of a pigment and crosslinked polyimide which offer low gloss advantages such as from about 1 to about 30 gloss units thereby providing matte images desired for certain printing or copying applications, especially wherein matte highlight or black documents are desired. Furthermore, with the toners of the present invention other advantages, such as low fusing temperature and low humidity sensitivity, are retained.
Illustrated in the following copending applications, the disclosures of each being totally incorporated herein by reference, are:
U.S. patent application Ser. No. 144,075 illustrates a toner composition comprised of a pigment and a crosslinked polyimide; and wherein the crosslinked polyimide can be obtained from the reaction of a peroxide with an unsaturated polyimide of the formula ##STR3## R is alkyl or oxyalkylene; and m represents the number of monomer segments present and is a number of from about 10 to about 1,000.
U.S. Pat. No. 5,348,830 illustrates a toner composition comprised of a pigment, and a thermotropic liquid crystalline polyimide of the formula ##STR4## wherein m represents the number of monomer segments present; X is a symmetrical moiety independently selected from the group consisting of phenyl, naphthyl, cyclohexyl, or bicycloaliphatic; and R is independently selected from the group consisting of alkyl, oxyalkylene and polyoxyalkylene.
U.S. patent application Ser. No. 144,956 illustrates a toner composition comprised of pigment, and polyimide of the formula ##STR5## wherein n represents the number of monomer segments, and is a number of from about 10 to about 1,000; and R is alkyl, oxyalkyl, or polyoxyalkyl.
U.S. Pat. No. 5,348,831 illustrates a toner composition comprised of pigment, and a polyester imide resin of the formula ##STR6## wherein n represents the number of segments present and is a number of from about 10 to about 10,000; R' is alkyl or alkylene; and R is independently selected from the group consisting of an oxyalkylene and polyoxyalkylene.
U.S. patent application Ser. No. 144,918 illustrates a toner composition comprised of pigment, and polyimide of the formula ##STR7## wherein m represents the number of monomer segments present; X is ##STR8## thus X can be benzophenone, oxydiphthalic, hexafluoropropane diphenyl, diphenyl sulfone, or biphenyl; X is attached to four imide carbonyl moleties; and R is independently selected from the group consisting of alkyl, oxyalkylene and polyoxyalkylene.
There are summarized and illustrated in the Encyclopedia of Polymer Science and Engineering, 2nd edition, Volume No. 12, published by Wiley (1985) other polyesterimides. Moreover, there are also disclosed in Advances in Polyimides Science in Technology, edited by Claudius Fegere et al., and published by Technomic Publishing (1993), unsaturated polyimides and certain crosslinked polyimides. However, these unsaturated and crosslinked imide resins are completely aromatic and useful as high performance materials, and there is no teaching therein relating to toners.
Also, in Eastman Kodak U.S. Pat. No. 5,266,429 there are illustrated charge transport (CTL) polyesterimide binders for photoreceptors.